1. Field of Invention
The invention relates to a control device for a vehicle.
2. Description of Related Art
There exists parallel hybrid systems in which both an engine and a motor/generator are attached to a transmission. Drive forces from both the engine and the motor/generator are transmitted to the transmission at the time of departure and acceleration, the motor/generator functions as a generator when a vehicle runs on a downhill road and when the vehicle brakes to make up for the engine brake effect, and a braking energy is recovered to enhance fuel consumption and to reduce a discharge of exhaust gas (see, for example, JP-A-9-215270).
In a vehicle with the hybrid system (HEV: Hybrid Electric Vehicle), there exists a starting control device for an internal combustion engine (see, for example, JP-A-11-153075). The starting control device restricts a maximum torque of the internal combustion engine at a vehicle departure time during a cold condition in order to reduce power consumption. The starting control restricts the maximum torque because when a motor is used to crank the internal combustion engine for starting in a cold condition in which the engine temperature is low, an engine speed is not readily increased due to a high viscosity of a lubricating oil. The battery is thus wastefully consumed until a predetermined engine speed is reached.
Incidentally, vehicles constructed such that the internal combustion engine is started by motor torque possibly suffer from a disadvantage in that a surplus torque is generated at the start of an engine that succeeds the driving of the motor. The surplus torque causes wheelspin and damage on a transmission. In particular, with such an arrangement, in which a torque converter is provided between the motor and the internal combustion engine and the transmission, a torque increasing action of the torque converter is high at the time of departure in a low speed. As such, a surplus torque is liable to be transmitted to a side of drive wheels via the transmission from the torque converter when the engine starts driving after the motor starts driving in order to add an engine torque to a motor torque.